Dhirubhai Ambani died intestate in July 2002, leaving the brothers to battle for control of a massive conglomerate that spans numerous industrial sectors.

Despite the feud, Reliance Industries in April reported a 47% rise in annual net profit to more than 75bn rupees ($1.7bn; £900m), mainly thanks to the core oil business.

Mrs Ambani said: "I am confident that both Mukesh and Anil will resolutely uphold the values of their father and work toward protecting and enhancing value for over three million shareholders of the Reliance Group."

The Ambanis own about one-third of Reliance, which is worth about 12% of the Bombay Stock Exchange.

Control of the flagship arm - Reliance Industries - along with IPCL goes to Mukesh, 48, while Anil, 46, takes Reliance Energy and the financial services division as well as telecoms.

E-mails

The brothers have vastly different personalities. Mukesh is said to be a conservative, reticent workaholic while Anil is more stylish, media friendly and is married to a former Bollywood star.

The Bombay stock market briefly rose above 7,000

In November, the simmering feud erupted into the open when Mukesh told a television reporter there were certain "ownership issues" in the "private domain" that remained unresolved, causing a media storm.

Confidential e-mail messages and internal boardroom documents were leaked to journalists indicating a major row over control of the flagship Reliance Industries.

Paranjoy Guha Thakurta, an economic analyst in Delhi, said part of the feud stemmed from Mukesh's displeasure at Anil's political ambitions and concern at his brother's grandiose plans for what is being touted as the world's largest gas-based power plant near Delhi.

Anil, Mr Thakurta said, was apparently upset that one of Mukesh's pet ventures, telecoms company Reliance Infocomm, was embroiled in a messy legal dispute with major financial implications.

Investment adviser SP Tulsian told Associated Press on Saturday: "The messy part of the settlement is over. A new era will start in Reliance."

India's Finance Minister P Chidambaram said: "I am happy that matters have been settled amicably. Both brothers have kept the interests of millions of shareholders in mind."